1. Field of the Invention
The present invention relates to the field of medical technology in general. In particular, the present invention relates specifically to an improved intraocular lens designed specifically such that the focal length between the lens and the retina can be varied in a manner similar to the manner the focal length of a natural lens varies. Known art may be found in U.S. Class 623, subclasses 5 and 6 as well as in other classes and subclasses.
2. Description of the Known Art
As will be appreciated by those skilled in the art, a replacement intraocular lens may be implanted to replace a natural lens for patients requiring such treatment as for example in cataract removal. These replacement surgeries have become more common recently as a preferential method for addressing certain ocular ailments. Details of a typical procedure are contained in U.S. Pat. No. 6,364,906 to Baikoff, the teachings of which are hereby expressly incorporated by reference.
A replacement intraocular lens consists of biocompatible material that may be characterized as having two sections. The first section is termed an optical part, which is the lens. The second section is termed a haptic part, which is the structure that holds the lens in position while keeping the anterior capsular bag taunt and annular in shape. Both these functions are important for proper vision to result from the replacement surgery.
The optical requirements for replacement lens have been well established. Most lens materials currently used also allow the surgeon to fold the lens during insertion so that it can be made to pass through a very small slit, 2 to 4 mm in length, in the eye to gain access into the capsular bag.
The haptic part is still evolving however. The haptic structure needs to contact the interior of the anterior capsular sac essentially for 300 to 360 degrees to properly stretch the sac to anchor the replacement lens properly while minimizing rupturing or tearing of the bag. Some early haptic structures had two connections to the lens and formed two loops. An example of this structure is shown in U.S. Pat. No. 4,494,254 to Lopez.
Later haptic structures used only one connection to the lens. Examples of such structures may be seen in U.S. Pat. No. 4,842,600 to Feaster; U.S. Pat. No. 4,950,290 to Kamerling; U.S. Pat. No. 5,133,751 to Bayer; and U.S. Pat. No. 6,364,906 to Baikoff. These haptic structures have one end secured in the lens structure. The other haptic end has a single spiral that leads into an annular section that forms a ring. The known haptic structures, whether with one or two connections to the lens, are essentially coplanar with the lens. That is, when the intraocular lens was implanted correctly, the annular coil or ring portion of the embedded haptic touched the inside of the capsular sac through a 300 to 360 degree arc and the lens portion was substantially in the same horizontal plane as the haptic portion.
Some haptic structures, for example, U.S. Pat. No. 4,842,600 to Feaster, had an adjustment for the diameter of the annular part, which was accomplished by affixing the diameter with slide holes on the ends of the haptic structure. Some others used horizontal tensioning of the annular part to obtain the correct diameter for maintaining contact with the capsular bag. For example, U.S. Pat. No. 4,950,290 to Kamerling; U.S. Pat. No. 5,133,751 to Bayer; and U.S. Pat. No. 6,364,906 to Baikoff.
U.S. Pat. No. 5,653,752 describes a method for adjusting the curvature of the corneal using intrastromal corneal rings. This work is only marginally relevant to the present invention which uses the natural focusing mechanism of the eye to adjust the lens position relative to the retina and also influences the shape of the capsular sac.
The intraocular replacement lens discussed heretofore attempted to simultaneously place the lens and hold it in correct position while also giving horizontal geometric stabilization to the capsular bag. The known art however fails to provide a suitable replacement structure that retains the ability of the implant recipient to be able to focus on both close and far objects as a natural lens does or that stabilizes both the horizontal and vertical geometries of the capsular bag. Thus, most implant recipients require corrective devices to achieve normal vision.
Thus, a need exists for an improved intraocular lens implant structure that can be moved to accommodate focal length adjustments in a fashion similar to that of a natural lens to retain the ability to focus on objects at different distances from the observer. It is also desirable to provide an interocular lens that stabilizes the capsular bag in both the vertical and horizontal axes. It is still further desirable to provide such stabilization conically to mimic the natural shape of the capsular bag. An improved replacement lens would permit the recipient to use their eyes as before and more particularly would enable the recipient to flex the lens to properly focus images upon their retina.